PROBLEM TO BE SOLVED: To provide medical illumination system and illumination method capable of minimizing the burden on the eyes of an operator during operation for an operated person, and supplying optimal illumination to a therapeutic room depending on the scene.SOLUTION: A medical illumination system 1 includes a medical illuminating lamp 10 illuminating a therapeutic part, and an indoor illumination device 20 illuminating the indoor space. The medical illuminating lamp 10 is configured to apply a light beam having a first color temperature. The indoor illumination device 20 is configured to apply a plurality of light beams having different color temperature, including a second color temperature belonging to a range of +1000K through -1000K, with reference to the first color temperature.